RESUMO
Loss-of-function mutations of cyclic-AMP response element binding protein, binding protein (CREBBP) are prevalent in lymphoid malignancies. However, the tumour suppressor functions of CREBBP remain unclear. We demonstrate that loss of Crebbp in murine haematopoietic stem and progenitor cells (HSPCs) leads to increased development of B-cell lymphomas. This is preceded by accumulation of hyperproliferative lymphoid progenitors with a defective DNA damage response (DDR) due to a failure to acetylate p53. We identify a premalignant lymphoma stem cell population with decreased H3K27ac, which undergoes transcriptional and genetic evolution due to the altered DDR, resulting in lymphomagenesis. Importantly, when Crebbp is lost later in lymphopoiesis, cellular abnormalities are lost and tumour generation is attenuated. We also document that CREBBP mutations may occur in HSPCs from patients with CREBBP-mutated lymphoma. These data suggest that earlier loss of Crebbp is advantageous for lymphoid transformation and inform the cellular origins and subsequent evolution of lymphoid malignancies.
Assuntos
Proteína de Ligação a CREB/deficiência , Proteína de Ligação a CREB/metabolismo , Transformação Celular Neoplásica/metabolismo , Células Progenitoras Linfoides/metabolismo , Linfoma/metabolismo , Células-Tronco Neoplásicas/metabolismo , Acetilação , Animais , Proteína de Ligação a CREB/genética , Proliferação de Células , Autorrenovação Celular , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Células Cultivadas , Dano ao DNA , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Predisposição Genética para Doença , Histonas/metabolismo , Linfangiogênese , Células Progenitoras Linfoides/patologia , Linfoma/genética , Linfoma/patologia , Linfopoese , Metilação , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação , Células-Tronco Neoplásicas/patologia , Fenótipo , Transdução de Sinais , Fatores de Tempo , Transcrição Gênica , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
BACKGROUND: B-cell precursor acute lymphoblastic leukemia (B-ALL) is amongst the leading causes of childhood cancer-related mortality. Its most common chromosomal aberration is the ETV6-RUNX1 fusion gene, with ~25% of ETV6-RUNX1 patients also carrying PAX5 alterations. METHODS: We have recreated this mutation background by inter-crossing Etv6-RUNX1 (Etv6 (RUNX1-SB)) and Pax5(+/-) mice and performed an in vivo analysis to find driver genes using Sleeping Beauty transposon-mediated mutagenesis and also exome sequencing. RESULTS: Combination of Etv6-RUNX1 and Pax5(+/-) alleles generated a transplantable B220 + CD19+ B-ALL with a significant disease incidence. RNA-seq analysis showed a gene expression pattern consistent with arrest at the pre-B stage. Analysis of the transposon common insertion sites identified genes involved in B-cell development (Zfp423) and the JAK/STAT signaling pathway (Jak1, Stat5 and Il2rb), while exome sequencing revealed somatic hotspot mutations in Jak1 and Jak3 at residues analogous to those mutated in human leukemias, and also mutation of Trp53. CONCLUSIONS: Powerful synergies exists in our model suggesting STAT pathway activation and mutation of Trp53 are potent drivers of B-ALL in the context of Etv6-RUNX1;Pax5(+/-).
Assuntos
Subunidade alfa 2 de Fator de Ligação ao Core/genética , Proteínas de Fusão Oncogênica/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Proteínas Proto-Oncogênicas c-ets/genética , Proteínas Repressoras/genética , Animais , Modelos Animais de Doenças , Janus Quinases/genética , Camundongos , Mutagênese , Fator de Transcrição PAX5/genética , Variante 6 da Proteína do Fator de Translocação ETSRESUMO
The introduction of highly selective ABL-tyrosine kinase inhibitors (TKIs) has revolutionized therapy for chronic myeloid leukemia (CML). However, TKIs are only efficacious in the chronic phase of the disease and effective therapies for TKI-refractory CML, or after progression to blast crisis (BC), are lacking. Whereas the chronic phase of CML is dependent on BCR-ABL, additional mutations are required for progression to BC. However, the identity of these mutations and the pathways they affect are poorly understood, hampering our ability to identify therapeutic targets and improve outcomes. Here, we describe a novel mouse model that allows identification of mechanisms of BC progression in an unbiased and tractable manner, using transposon-based insertional mutagenesis on the background of chronic phase CML. Our BC model is the first to faithfully recapitulate the phenotype, cellular and molecular biology of human CML progression. We report a heterogeneous and unique pattern of insertions identifying known and novel candidate genes and demonstrate that these pathways drive disease progression and provide potential targets for novel therapeutic strategies. Our model greatly informs the biology of CML progression and provides a potent resource for the development of candidate therapies to improve the dismal outcomes in this highly aggressive disease.
